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Get the M6532 chip implementation to the point of being OK to test.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2019-05-27 13:21:35 +01:00
parent d37f130577
commit 90bfac83d5
2 changed files with 107 additions and 85 deletions
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39
M6532/inc/M6532.h
View File

@ -3,6 +3,8 @@
#include <cstdint>
#include <ClockedChip.h>
#include <Signal.h>
#include <Ram.h>
/*
PIA 6532 combined timer, IO and 128 bytes RAM
@ -190,16 +192,16 @@ namespace EightBit {
put into an OFF-STATE during Reset. Interrupt capability is disabled with the RES signal. The RES signal
must be held low for at least one clock period when reset is required.
*/
PinLevel& RES() { return m_res; }
DECLARE_PIN_INPUT(RES)
/*
/* _
Read/Write (R/W)
The R/W signal is supplied by the microprocessor array and is used to control the transfer of data to and
from the microprocessor array and the 6532. A high on the R/W pin allows the processor to read (with proper
addressing) the data supplied by the 6532. A low on the R/W pin allows a write (with proper addressing) to
the 6532.
*/
PinLevel& RW() { return m_rw; }
DECLARE_PIN_INPUT(RW)
/* ___
Interrupt Request (IRQ)
@ -207,7 +209,7 @@ namespace EightBit {
an interrupt from the 6532. An external pull-up device is required. The IRQ pin may be activated by a
transition on PA7 or timeout of the interval timer.
*/
PinLevel& IRQ() { return m_irq; }
DECLARE_PIN_OUTPUT(IRQ)
/*
Data Bus (D0-D7)
@ -215,7 +217,7 @@ namespace EightBit {
allow transfer of data to and from the microprocessor array. The output buffers remain in the off state except
when a Read operation occurs and are capable of driving one standard TTL load and 130 pf.
*/
uint8_t& data() { return m_data; }
auto& DATA() { return m_data; }
/*
Peripheral Data Ports
@ -236,28 +238,32 @@ namespace EightBit {
/*
Address Lines (A0-A6)
There are 7 address pins. In addition to these 7, there is 9 RAM SELECT pin. These pins, A0-A6 and RAM
There are 7 address pins. In addition to these 7, there is a RAM SELECT pin. These pins, A0-A6 and RAM
SELECT, are always used as addressing pins. There are two additional pins which are used as CHIP
SELECTS. They are pins CS1 and CS2.
*/
uint8_t& address() { return m_address; }
// RAM SELECT, active low
PinLevel& RS() { return m_rs; }
DECLARE_PIN_INPUT(RS)
// CHIP SELECT 1, active high
PinLevel& CS1() { return m_cs1; }
DECLARE_PIN_INPUT(CS1)
// CHIP SELECT 2, active low
PinLevel& CS2() { return m_cs2; }
DECLARE_PIN_INPUT(CS2)
void tick();
bool activated() { return powered() && selected(); }
bool selected() { return raised(CS1()) && lowered(CS2()); }
virtual void initialise() final;
Signal<EventArgs> Accessing;
Signal<EventArgs> Accessed;
private:
void step();
void reset();
private:
enum EdgeDetect { Positive, Negative };
enum TimerIncrement { One = 1, Eight = 8, SixtyFour = 64, OneThousandAndTwentyFour = 1024 };
@ -268,8 +274,6 @@ namespace EightBit {
auto& IF() { return m_interruptFlags; }
bool selected() { return raised(CS1()) && lowered(CS2()); }
uint8_t m_address;
uint8_t m_data;
@ -281,13 +285,6 @@ namespace EightBit {
uint8_t m_drb;
uint8_t m_ddrb;
PinLevel m_res;
PinLevel m_rw;
PinLevel m_irq;
PinLevel m_rs;
PinLevel m_cs1;
PinLevel m_cs2;
Ram m_ram = 0x80;
bool m_allowTimerInterrupts;

153
M6532/src/M6532.cpp
View File

@ -4,98 +4,123 @@
#include <cassert>
EightBit::M6532::M6532() noexcept {
Ticked.connect([this](EightBit::EventArgs&) {
step();
});
}
void EightBit::M6532::tick() {
DEFINE_PIN_LEVEL_CHANGERS(RES, M6532);
DEFINE_PIN_LEVEL_CHANGERS(RW, M6532);
DEFINE_PIN_LEVEL_CHANGERS(IRQ, M6532);
DEFINE_PIN_LEVEL_CHANGERS(RS, M6532);
DEFINE_PIN_LEVEL_CHANGERS(CS1, M6532);
DEFINE_PIN_LEVEL_CHANGERS(CS2, M6532);
if (selected()) {
void EightBit::M6532::step() {
// Process interrupts
resetCycles();
if (--m_currentIncrement == 0) {
m_currentIncrement = m_timerIncrement;
--m_timerInterval;
}
if (m_allowPA7Interrupts && (PA() & 0x80))
IF() &= 0x40;
if (!activated())
return;
if (m_allowTimerInterrupts && (m_timerInterval == 0))
IF() &= 0x80;
Accessing.fire(EventArgs::empty());
const auto read = raised(RW());
const auto write = lowered(RW());
assert(read == !write);
if (lowered(RES())) {
reset();
raise(RES());
return;
}
const auto ram = lowered(RS());
if (ram) {
if (--m_currentIncrement == 0) {
m_currentIncrement = m_timerIncrement;
--m_timerInterval;
}
auto& cell = RAM().reference(address() & 0x7f);
read ? data() = cell : cell = data();
const bool interruptPA7 = m_allowPA7Interrupts && (PA() & Bit7);
if (interruptPA7)
setFlag(IF(), Bit6);
const bool interruptTimer = m_allowTimerInterrupts && (m_timerInterval == 0);
if (interruptTimer)
setFlag(IF(), Bit7);
interruptPA7 || interruptTimer ? lower(IRQ()) : raise(IRQ());
const auto read = raised(RW());
const auto write = lowered(RW());
assert(read == !write);
const auto ram = lowered(RS());
if (ram) {
auto& cell = RAM().reference(address() & 0x7f);
read ? DATA() = cell : cell = DATA();
} else {
const auto a0 = address() & 0b00001;
const auto a1 = address() & 0b00010;
const auto a2 = address() & 0b00100;
const auto a3 = address() & 0b01000;
const auto a4 = address() & 0b10000;
const auto portControls = a2 == 0;
const auto otherControls = a2 == 1;
if (portControls) {
switch (a0 | a1) {
case 0b00:
// R/W output reg A
break;
case 0b01:
read ? DATA() = DDRA() : DDRA() = DATA();
break;
case 0b10:
// R/W output reg B
break;
case 0b11:
read ? DATA() = DDRB() : DDRB() = DATA();
break;
}
} else {
const auto a0 = address() & 0b00001;
const auto a1 = address() & 0b00010;
const auto a2 = address() & 0b00100;
const auto a3 = address() & 0b01000;
const auto a4 = address() & 0b10000;
if (read && !a4 && a2) {
m_allowPA7Interrupts = !a1;
m_edgeDetection = a0 ? Positive : Negative;
}
const auto portControls = a2 == 0;
const auto otherControls = a2 == 1;
if (read && a2 && a0) {
DATA() = IF();
clearFlag(IF(), Bit6);
}
if (portControls) {
m_allowTimerInterrupts = !!a3;
switch (a0 | a1) {
if (write && a4) {
m_timerInterval = DATA();
switch (a1 | a0) {
case 0b00:
// R/W output reg A
m_timerIncrement = One;
break;
case 0b01:
read ? data() = DDRA() : DDRA() = data();
m_timerIncrement = Eight;
break;
case 0b10:
// R/W output reg B
m_timerIncrement = SixtyFour;
break;
case 0b11:
read ? data() = DDRB() : DDRB() = data();
m_timerIncrement = OneThousandAndTwentyFour;
break;
}
} else {
if (read && !a4 && a2) {
m_allowPA7Interrupts = !a1;
m_edgeDetection = a0 ? Positive : Negative;
}
if (read && a2 && a0)
data() = IF() & (0x80 & 0x40);
m_allowTimerInterrupts = !!a3;
if (write && a4) {
m_timerInterval = data();
switch (a1 | a0) {
case 0b00:
m_timerIncrement = One;
break;
case 0b01:
m_timerIncrement = Eight;
break;
case 0b10:
m_timerIncrement = SixtyFour;
break;
case 0b11:
m_timerIncrement = OneThousandAndTwentyFour;
break;
}
m_currentIncrement = m_timerIncrement;
}
m_currentIncrement = m_timerIncrement;
clearFlag(IF(), Bit7);
}
}
}
}
void EightBit::M6532::initialise() {
Accessed.fire(EventArgs::empty());
}
void EightBit::M6532::reset() {